During the operation of an indoor swimming pool, halogen-based disinfectants such as chlorine or bromine are utilized to react with and remove harmful bacteria and organic materials from the swimming pool water. Compounds referred to as disinfectant by-products (DBPs) are formed as a consequence of the disinfection reactions. Trichloramine, one of the most important of these compounds, off-gasses from swimming pool water and accumulates as a dense gas in the air just above the pool waterline. Trichloramine is an extreme irritant. It causes eye, nose and throat irritation, has been linked to asthma-like symptoms, and causes corrosion on pool building components and equipment. Organic DBPs, such as trihalomethanes, are also present in the air in indoor swimming pools and this class of compounds has been linked to an increased risk for certain types of cancer.
Several devices, systems and methods for removing or controlling the concentration of gaseous contaminants in indoor swimming pools are known in the art. Some devices, systems and methods are directed toward preventing the formation of DBP contaminants in the water by eliminating or minimizing the introduction of nitrogen-containing organic compounds into pool water (nitrogen-containing compounds which react with chlorine or bromine used for disinfecting pool water are responsible for forming these contaminants); these methods have proved to be impractical because swimmers are the primary source of nitrogen-containing compounds. Other systems rely on medium-pressure ultraviolet (UV) light devices to destroy DBP contaminants in the water in the water treatment room before they volatilize and appear in the air; these systems have been demonstrated to be less than totally effective because the creation and volatilization of DBPs can occur before the water can be recycled back to the UV unit. The most common method for controlling off-gassed DBPs relies on the air handling system (HVAC) in the natatorium (swimming pool enclosure) to progressively dilute the concentration of gaseous contaminants through multiple air changes utilizing a large percentage of outside air, until the concentration of contaminants no longer poses a health risk; these methods frequently fail because the energy penalty for heating, cooling and/or dehumidifying large quantities of outside air is too great.
Also known in the art are systems that utilize pool-side exhaust devices (pool-side gutters with integral exhaust features or deck-mounted pool-side exhaust devices) to exhaust contaminated air from the natatorium. These exhaust systems rely on the HVAC system in the natatorium to move contaminated air across the surface of the swimming pool to a position close enough to the gutter to enable the exhaust system to capture and remove, by suction, the contaminated air presented.[10] One such system is described by Baker in U.S. Patent Application No. US20110107510A1 and US20110244782A1. These systems are not capable, on their own, of removing contaminated air from the surface of a pool due to the fact that suction returns cannot independently draw in air and contaminants from a distance of more than a few feet from the face of the return. For example, Huang et al. in U.S. Pat. No. 7,819,727 discloses that the operational distance of push flow is much larger than that of pull (suction) flow and that push-pull systems are more efficient.
These suction systems are even less capable of drawing contaminated air in a direction opposed to the direction of the air circulation caused by the HVAC system; they are, in fact, dependent upon the HVAC system circulation to push contaminated air in the direction of the gutter or pool-side exhaust. These systems are not designed to selectively place airflow in the area where it is needed (the area just above the water surface where the concentration of DBPs is highest), are not designed to localize and control the air supply such as to minimize the amount of air employed to remove contaminated air from the surface of a pool, and are not designed to minimize turbulent mixing of the supplied clean air with the contaminated air. Turbulent mixing of the contaminated air with clean air results in contaminated air being recirculated throughout the natatorium.
Gutter or pool-side exhaust systems that rely on the configuration of the HVAC system to move air in such a way as to present contaminated air to a gutter or pool-side exhaust, are capable of removing gaseous contaminants from the area just above the waterline if an elaborate natatorium HVAC system is carefully designed, maintained and operated. Since gutter exhaust systems rely on complementary functioning of the HVAC system, they are not self-contained. The HVAC system in a natatorium has many functions: to control humidity in the airspace; to control temperature in the airspace; to maintain a negative pressure in the airspace; to provide dry, fresh air to wash over windows, skylights and doors; and to provide dry, fresh air to spectators. Requiring the HVAC system to perform all these normal functions, plus the function of sweeping the pool surface in a carefully controlled manner with minimal expenditure of energy and in the preferred direction to drive contaminated air to the gutter or pool-side return and exhaust, presents a difficult and complex design challenge. It requires the use of large quantities of air and results in an unnecessarily complex and expensive system with high operational costs.
There remains a need in the art for devices and methods that successfully eliminate contaminated air and are efficient, self-contained, easy to build, and easy to integrate into a natatorium system.